What do scores mean? What to do if you score

low on an IQ test?

Binet

Terman

Study, and develop self-discipline and

attention span.

Remove your genes from the

population(eugenics).

▪ Lewis Terman, of Stanford University, began with a different assumption than Binet; Terman felt that intelligence was unchanging and innate (genetic).

▪ He created the “Stanford-Binet Test”

Nazi Propaganda: “Qualitative decline in the population...It will come to this if individuals with lesser value have four

children and those of higher value have two."

George Bernard Shaw –a Nobel Prize and Oscar-winning Irish author and

philosopher.

Virginia’s test case – Carrie Buck

“A probable potential parent of socially

inadequate offspring.”

http://www.hsl.virginia.edu/historical/eugenic

s/3-buckvbell.cfm

•At her trial, she was said to have “a record of immorality, prostitution, untruthfullness and syphillis.”•In private writings, the director of the home where she lived described her family as: “These people belong to the shiftless, ignorant and worthless class of anti-social whites of the South

http://www.eugenicsarchive.org/eugenics/

Tomorrow’s Children - 1934

Some well-known individuals who supported eugenics:

Alexander Graham BellJohn D. RockefellerTheodore RooseveltWoodrow WilsonWinston ChurchillMargaret Sanger

Terman (from Stanford) and his IQ

Test

• A 8 year old has a mental age of 10, what is her IQ?

• A 12 year old has the mental age of 9, what is his IQ?

• Used Binet’s research to construct the modern day IQ test called the Stanford-Binet Test.

Coming to America• The idea of IQ testing became popular

in America for three reasons:– A huge increase in immigration

– New laws requiring universal education

– Military assessing new recruits for WWI

– Despite its utility, IQ testing had a big downside. Tests ended up reinforcing prevailing prejudices about race and gender.

– Ignored was the fact that environmental disadvantages limit the full development of people’s intellectual abilities.

Changes in how intelligence is

defined: Binet v. Terman

• Binet: intelligence malleable

• Terman: intelligence is inherited and stable

Modern Tests of Mental Abilities

• Wechsler Adult Intelligence Scale (WAIS) consists of 11 subtests and cues us in to strengths by using…..

Factor Analysis

• Later - Wechsler Intelligence Scale for Children (WISC), an intelligence test for preschoolers.

Assessing Intelligence: Sample

Subscores from the WAIS

From Thorndike and Hagen, 1977

VERBAL

General Information

Similarities

Arithmetic Reasoning

Vocabulary

Comprehension

Digit Span

PERFORMANCE

Picture Completion

Picture Arrangement

Block Design

Object Assembly

Digit-Symbol Substitution

Aptitude v. Achievement TestsAptitude

• A test designed to predict a person’s future performance.

• The ability for that person to learn.

Achievement

• A test designed to assess what a person has learned.

16

Aptitude and Achievement Tests

Q: What is the correlation between SAT scores and

IQ scores?

What are the 3 most important considerations when testing?

How do we construct Intelligence tests?

Tests must be:

• Valid

• Reliable

• Standardized

Validity & ReliabilityValidity: The extent to which a test

measures what it is supposed to measure.

• Content Validity: does the test actually sample a behavior it is measuring?

• Predictive Validity: does the test accurately predict future behavior?

Reliability: The extent which a test yields consistent results over time.

Test-Retest Reliability

Questionnaire (Completed 9/20)

___ I feel I do not have much proud of.

___ On the whole, I am satisfied with myself

___ I certainly feel useless at times

___ At times I think I am no good at all

___ I have a number of good qualities

___ I am able to do things as well as others

Questionnaire (Completed 9/27)

___ I feel I do not have much proud of.

___ On the whole, I am satisfied with myself

___ I certainly feel useless at times

___ At times I think I am no good at all

___ I have a number of good qualities

___ I am able to do things as well as others

4

21

4

3

4

41

1

4

4

▪ Administering the same test to the same set of examinees on two separate occasions.

The extent which a test yields consistent results over time.Reliability

3

Standardization• Defining uniform testing procedures and

scores by comparing scores to a pre-tested group.

• Tests like WAIS are periodically re-standardized. (The average intelligence score in 1920 would only score a 76 by today’s standard.)

• This also helps to eradicate biases due to gender, race, culture, socio-economic status, special-needs, etc.

22

Heritability•Heritability refers to the extent to which the differences among people are attributable to genes.

•Mathematical formula, with results varying from 0-100.

•In an identical environment, and difference would result in a heritability of 100. (Correlations of .7 or above are considered strong evidence of genetic influence.)

•As environments become more similar, heredity as a source of differences necessarily becomes more important.

•Question: If all schools were of the same quality, all families equally loving, and all neighborhoods equally healthy, would heritability increase or decrease? Why?

•Heritability of height is how much variance (differences,) exist groups of individuals, due to genetic factors. •In Anglo-American studies, heritability has been found to be about 0.80. •Much lower estimates have been found in West Africa (0.56) –why?

Heritability of Body Height & Environment

Anglo-American West Africa

Heritability

of Height

0.80 0.56

Source: Silventoinen K et al., AJPH 2000

Heritability of Body Height & Environment

Because the much more prevalent and severe environmental factors in developing countries, largely malnutrition and recurrent/chronic infections throughout childhood, interfere with the ability of individuals to reach their full genetic “height potential.”

Anglo-American West Africa

Heritabilityof Height

0.80 0.56

Source: Silventoinen K et al., AJPH 2000

Mark Twain explains it best using the barrel example…

Genetic Differences

▪ Genetic differences and environmental impact

Variation within group

Variation within group

Difference within group

Poor soil Fertile soil

Seeds